In order to set cookies in an AgentBuilder you need to create a CookieStore, however ureq doesn't re-export it: to do so you need to explicitly depend on either the cookie or the cookie_store crates.

However this is not just poor ergonomics, it creates a semver hazard: since the direct dependency is not linked to ureq's, and 0.x updates are considered not compatible semver-wise, any update to ureq's cookie dependency is a breaking change¹ because it results in two copies of the cookie/cookie_store crate.

This in particular happened with the 2.5.0 update, which broke a project of mine that used ureq with cookies.
My preferred fix would be to expose CookieStore and allow using that instead of depending on an external non-synced crate. Note that Cookie is already re-exported.